What is cloud computing and is that something that should be considered rather than building a data center?

The CIO has called you to her office. She has been hearing about data centers and is wondering if that is something our company should consider. (The server room is at max capacity so a decision needs to be made if we should add on to current space or build a dedicated building.) Growth of our company is expected to double in the next 5 years.
You are responsible for researching this topic and submitting a report to her as soon as possible. Some of the things your report should include are as follows:
1.What is a data center?
2.What kind of environmental factors should be considered? (size, cooling, heating, etc)
3.Is physical security an issue?
4.What is cloud computing and is that something that should be considered rather than building a data center?
5.Include 3 other things not already discussed that she should know about data centers. (give lots of details, not bullets)
6.Conclusion does it make sense for our business to invest in a data center or not?